Draft



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No. 890,508. l Patented Oct. 2, 1888.

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n No. 390,508. Patented ont. 2, 1888.

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SPECIFICATION ferritin;r pari; of Letters Patent No.' 390,503, date? @eroico-r 2,1888.

To all whom it may con/cera.-

Be it known that we, Grammes D.l Mosnnn and GILMAN W. BRO\\N,'residents, respect ively, ol' Amesbury and of Test Newbury,

both in the county oi Esserrand State of Mas` sachusetts, have invented certain new and use ful Improvements in Draft Appliances for Stearn-Boilcr Furnaces, ofwhich the following is aspeciticatiou. l

This invention has for'its object to provide .simple and effective means for creating draft through the furnaces of marine and other boilers; and ityconsists, iirst, in a :'otary fan or blower located at a suitable point in the iue I5 or passage through which the products of combustion pass from a furnace, saidl blower having hollow blades formed to permit the continuous passage of air, the arrangement being such that cool external air-ds admitted toand o passes through said blades,'wl1ich are thereby protected from theintense heat to which they are subjected.

The invention also consists in certain details of construction, all of which we will now pro- Of the accompanying drawings, forming a part of this specification, Figure 1 represents 1 a front elevation of a portion of the-.flue or passage between the furnace and smoke-stack of Fig. 2 represents a. section on line ac fr, Fig'l. Fig. 3 represents a perspeo tive view ofaportion of an improved fan and a portion ofthe due casing. Fig. It represents y arsectional view of o'nc of the fan-blades. The sagme letters of reference indicate the saine parts in` all the figures.,

In the drawings, a c represent the tubes th rough which the products of combustion are' conducted through a steam boiler from the 4o furnace to the stack b 4of. a' steanrboiler. In the easing d, connecting said-tubes and stack7 we place a rotary fan, the blades c c oi' which are hollow, their inner ends opening to the external air th rough slots c' in a ll'rusto-conical g5 diaphragm, f, which is attached to the bases `of the' bladesand to the shaft e,which rotates the fan.- The outer ends Vof said blades open into the casing (1,.so that outside airpassing through the blades mingles in said casing with v.Stlie products of vcombustion in said casing and Srl-inl No. 265.663. (Xo model.)

' passes to the stack.V The outer side oi the casing d has an opening, d', the margin of which is in theelosest possible proximity to the outer edge of the diaphragm f, so as to prevent as fully as possible the admissionof outside air into the casing around said diaphragm with- 'out being in contact with said diaphragm, which, 'of course, rotates with the fan and prevents outside air from passing into the casing d between the fans.

The sha-ft c, which rotates the fan, is jouu naled in bearings z' i, one of which projects into the diaphragmfand supports said shai't c are attached. Said shaft may be rotated by any suitable means, and is here 'shown as p rovided with acrank, k', adapted to be connected with an engine of any suitable type. The shaft e has a longitudinal passage, m, which is open at one end to the outside air and coinmunicates with an air'- space, s, between the in ner side of the hub a and cap, a', attached jto the blades c., The airfspace's communicates with the ai r-.passages in the fans through openings in the bases of the fans.k Air is thus which it is subjected.

We prefer to cover the blades with asbestos paper, p, or other suitable non-conductor of heat, suitably secured to said blades, as a means for additionally protecting the blades from the heated products of combustion. The exposed surface of the 'cap n. may also be protected by asbestus paper, p', as shown in Fig. 2.

It will be seen that the rotation of theiiauv creates a draft in the casing d, while the constautypassage of c ool air through the blades of the fau prevents said biades from being injuredbythe heat. Our improvement there fore makes the use of a fan practicable as a means for forcing a draft, and furnishes a simple and comparatively inexpensivesubstitute for the complicated, expensive, aud dangerous forced-draft systems now in use.

It is obvious that the form and arraugexinent ously modified without departing from the spirit of our invention.. g

We do not limit ourselves to a fan arranged vclose to the hub or spider j, to which the blades caused to pass continually th rough the hub of y the fante protect said hub from the hentto yotthe fan and its diaphragm f may be vari- 'l' Ofi gilde, whereby cool air is enabled to .iil'close proximity to an opening in thc flue-casing and provided with a diaphragm, as shown, 'for the fan may'in some cases be placed within the flue1 or stack at adistance, from the casing and receive air into its blades through the hollow shaft'which rotates the fan.

Weclaim- 1. The combination, with a flue or conduit for the products of combustion from a boilerfurnace, of a rotary fan within said flue having hollow blades', and connections between said'blades and the atmosphere outside of the )ass through the blades, as' set forth. 1 2. The combination, with a flue or conduit for the products of combustion from a boilerfurnace, of a rotary fan within said flue having hollow blades, connections between said blades and the atmosphere outside of the iiue, whereby cool air is enabled to pass through the blades, a shaft supporting said fan, and a motor connected with said shaft outside of the flue, whereby the shaft and-fan are rotated, as setforth.

3..l The combination, witha tlue or conduit taining air-passages, and a diaphragmsecured to the fan as a means for preventing air from lpassing between the blades, said. diaphragm having openings for the admission of air to said air-passages, as set forth.

5. A rotary fan having hollow blades containing airpassages,and a diaph ragrn arranged to prevent air from passing between the blades,y said diaphragm having openings for the admission of air into the blades, combined with a casing having au opening coinciding with said diaphragm, as set forth. l

In testimony whereof we have signed our names to this specification, in the presence of two subscribing witnesses, this 23d day of February, A. D. 1,888. 1

` CHARLES D. MOSHER.

GILMAN W. BROWN. Witnesses:

C; F. BROWN,

A. D. HARRISON. 

